/*
Script: Namespace.js
Namespace utility

Copyright:
Copyright (c) 2009 Maxime Bouroumeau-Fuseau

License:
MIT-style license.
Version:
1.1
*/

/*jslint evil : true */
/*global Namespace, XMLHttpRequest, ActiveXObject, window, document */

var Namespace = (function() {

var _listeners = {};
var _includedIdentifiers = [];

/**
* Returns an object in an array unless the object is an array
*
* @param mixed obj
* @return Array
*/
var _toArray = function(obj) {
// checks if it's an array
if (typeof(obj) == 'object' && obj.sort) {
return obj;
}
return Array(obj);
};

/**
* Creates an XMLHttpRequest object
*
* @return XMLHttpRequest
*/
var _createXmlHttpRequest = function() {
var xhr;
        try { xhr = new XMLHttpRequest(); } catch(e) {
            try { xhr = new ActiveXObject("Msxml2.XMLHTTP.6.0"); } catch(e2) {
                try { xhr = new ActiveXObject("Msxml2.XMLHTTP.3.0"); } catch(e3) {
                    try { xhr = new ActiveXObject("Msxml2.XMLHTTP"); } catch(e4) {
                        try { xhr = new ActiveXObject("Microsoft.XMLHTTP"); } catch(e5) {
                            throw new Error( "This browser does not support XMLHttpRequest." );
}
}
}
}
}
return xhr;
};

/**
* Checks if an http request is successful based on its status code.
* Borrowed from dojo (http://www.dojotoolkit.org).
*
* @param Integer status Http status code
* @return Boolean
*/
var _isHttpRequestSuccessful = function(status) {
return (status >= 200 && status < 300) || // Boolean
status == 304 || // allow any 2XX response code
status == 1223 || // get it out of the cache
(!status && (window.location.protocol == "file:" || window.location.protocol == "chrome:") ); // Internet Explorer mangled the status code
};

/**
* Creates a script tag with the specified data as content
*
* @param String data The content of the script
*/
var _createScript = function(data) {
var script = document.createElement('script');
script.type = 'text/javascript';
script.text = data;

        if (typeof window.execScript === "object") { // According to IE
            window.execScript(data);
        } else {
            try { // Attempt body insertion
                document.body.appendChild(script);
            } catch (e) { // Fall back on eval
                window['eval'](data);
            }
        }
};

/**
* Dispatches an event
*
* @param String eventName
* @param Object properties
*/
var _dispatchEvent = function(eventName, properties) {
if (!_listeners[eventName]) { return; }
properties.event = eventName;
for (var i = 0; i < _listeners[eventName].length; i++) {
_listeners[eventName][i](properties);
}
};

/**
* Creates an Object following the specified namespace identifier.
*
* @public
* @param String identifier The namespace string
* @param Object klasses (OPTIONAL) An object which properties will be added to the namespace
* @return Object The most inner object
*/
var _namespace = function(identifier) {
var klasses = arguments[1] || false;
var ns = window;

if (identifier !== '') {
var parts = identifier.split(Namespace.separator);
for (var i = 0; i < parts.length; i++) {
if (!ns[parts[i]]) {
ns[parts[i]] = {};
}
ns = ns[parts[i]];
}
}

if (klasses) {
for (var klass in klasses) {
                if (klasses.hasOwnProperty(klass)) {
ns[klass] = klasses[klass];
                }
}
}

_dispatchEvent('create', { 'identifier': identifier });
return ns;
};

/**
* Checks if the specified identifier is defined
*
* @public
* @param String identifier The namespace string
* @return Boolean
*/
_namespace.exist = function(identifier) {
if (identifier === '') { return true; }

var parts = identifier.split(Namespace.separator);
var ns = window;
for (var i = 0; i < parts.length; i++) {
if (!ns[parts[i]]) {
return false;
}
ns = ns[parts[i]];
}

return true;
};

/**
* Maps an identifier to a uri. Is public so it can be overriden by custom scripts.
*
* @public
* @param String identifier The namespace identifier
* @return String The uri
*/
_namespace.mapIdentifierToUri = function(identifier) {
var regexp = new RegExp('\\' + Namespace.separator, 'g');
return Namespace.baseUri + identifier.replace(regexp, '/') + '.js';
};

/**
* Loads a remote script atfer mapping the identifier to an uri
*
* @param String identifier The namespace identifier
* @param Function successCallback When set, the file will be loaded asynchronously. Will be called when the file is loaded
* @param Function errorCallback Callback to be called when an error occurs
* @return Boolean Success of failure when loading synchronously
*/
var _loadScript = function(identifier) {
var successCallback = arguments[1];
var errorCallback = arguments[2];
var async = typeof successCallback === "function";
var uri = _namespace.mapIdentifierToUri(identifier);
var event = { 'identifier': identifier, 'uri': uri, 'async': async, 'callback': successCallback };

var xhr = _createXmlHttpRequest();
xhr.open("GET", uri, async);

if (async) {
xhr.onreadystatechange = function() {
if (xhr.readyState == 4) {
if (_isHttpRequestSuccessful(xhr.status || 0)) {
_createScript(xhr.responseText);
_dispatchEvent('include', event);
successCallback();
return;
}
event.status = xhr.status;
_dispatchEvent('includeError', event);
                    if (typeof errorCallback === "function") {
                        errorCallback();
                    }
}
};
}

xhr.send(null);

if (!async) {
if (_isHttpRequestSuccessful(xhr.status || 0)) {
_createScript(xhr.responseText);
_dispatchEvent('include', event);
return true;
}
event.status = xhr.status;
_dispatchEvent('includeError', event);
return false;
}
};

/**
* Includes a remote javascript file identified by the specified namespace string. The identifier
* must point to a class. Separators in the string will be converted to slashes and the .js extension will be appended.
*
* @public
* @param String identifier The namespace string
* @param Function callback (OPTIONAL) A function to call when the remote script has been included
*/
_namespace.include = function(identifier) {
var successCallback = arguments[1] || false;
var errorCallback = arguments[2] || false;

// checks if the identifier is not already included
if (_includedIdentifiers[identifier]) {
            if (typeof successCallback === "function") { successCallback(); }
return true;
}

if (successCallback) {
_loadScript(identifier, function() {
_includedIdentifiers[identifier] = true;
successCallback();
}, errorCallback);
} else {
if (_loadScript(identifier)) {
_includedIdentifiers[identifier] = true;
return true;
}
return false;
}
};

/**
* Imports properties from the specified namespace to the global space (ie. under window)
*
* The identifier string can contain the * wildcard character as its last segment (eg: com.test.*)
* which will import all properties from the namespace.
*
* If not, the targeted namespace will be imported (ie. if com.test is imported, the test object
* will now be global). If the targeted object is not found, it will be included using include().
*
* @public
* @param String identifier The namespace string
* @param Function callback (OPTIONAL) A function to call when the process is completed (including the include() if used)
* @param Boolean autoInclude (OPTIONAL) Whether to automatically auto include the targeted object is not found. Default is Namespace.autoInclude
*/
_namespace.use = function(identifier) {
var identifiers = _toArray(identifier);
var callback = arguments[1] || false;
var autoInclude = arguments.length > 2 ? arguments[2] : Namespace.autoInclude;
var event = { 'identifier': identifier };
        var parts, target, ns;

for (var i = 0; i < identifiers.length; i++) {
identifier = identifiers[i];

parts = identifier.split(Namespace.separator);
target = parts.pop();
ns = _namespace(parts.join(Namespace.separator));

if (target == '*') {
// imports all objects from the identifier, can't use include() in that case
for (var objectName in ns) {
                    if (ns.hasOwnProperty(objectName)) {
window[objectName] = ns[objectName];
                    }
}
} else {
// imports only one object
if (ns[target]) {
// the object exists, import it
window[target] = ns[target];
} else {
// the object does not exist
if (autoInclude) {
// try to auto include it
if (callback) {
_namespace.include(identifier, function() {
window[target] = ns[target];

if (i + 1 < identifiers.length) {
// we continue to unpack the rest from here
_namespace.unpack(identifiers.slice(i + 1), callback, autoInclude);
} else {
// no more identifiers to unpack
_dispatchEvent('use', event);
                                    if (typeof callback === "function") {
                                        callback();
                                    }
}
});
return;
} else {
_namespace.include(identifier);
window[target] = ns[target];
}
}
}
}

}

// all identifiers have been unpacked
_dispatchEvent('use', event);
        if (typeof callback === "function") { callback(); }
};

/**
* Binds the include() and unpack() method to a specified identifier
*
* @public
* @param String identifier The namespace identifier
* @return Object
*/
_namespace.from = function(identifier) {
return {
/**
* Includes the identifier specified in from()
*
* @see Namespace.include()
*/
include: function() {
var callback = arguments[0] || false;
_namespace.include(identifier, callback);
},
/**
* Includes the identifier specified in from() and unpack
* the specified indentifier in _identifier
*
* @see Namespace.use()
*/
use: function(_identifier) {
var callback = arguments[1] || false;
if (_identifier.charAt(0) == '.') {
_identifier = identifier + _identifier;
}

if (callback) {
_namespace.include(identifier, function() {
_namespace.use(_identifier, callback, false);
});
} else {
_namespace.include(identifier);
_namespace.use(_identifier, callback, false);
}
}
};
};

/**
* Registers a namespace so it won't be included
*
* Idea and code submitted by Nathan Smith (http://github.com/smith)
*
* @param String|Array identifier
*/
_namespace.provide = function(identifier) {
var identifiers = _toArray(identifier);

for (var i = 0; i < identifiers.length; i++) {
if (!(identifier in _includedIdentifiers)) {
_dispatchEvent('provide', { 'identifier': identifier });
_includedIdentifiers[identifier] = true;
}
}
};

/**
* Registers a function to be called when the specified event is dispatched
*
* @param String eventName
* @param Function callback
*/
_namespace.addEventListener = function(eventName, callback) {
if (!_listeners[eventName]) { _listeners[eventName] = []; }
_listeners[eventName].push(callback);
};

/**
* Unregisters an event listener
*
* @param String eventName
* @param Function callback
*/
_namespace.removeEventListener = function(eventName, callback) {
if (!_listeners[eventName]) { return; }
for (var i = 0; i < _listeners[eventName].length; i++) {
if (_listeners[eventName][i] == callback) {
delete _listeners[eventName][i];
return;
}
}
};

/**
* Adds methods to javascript native's object
* Inspired by http://thinkweb2.com/projects/prototype/namespacing-made-easy/
*
* @public
*/
_namespace.registerNativeExtensions = function() {
/**
* @see Namespace()
*/
String.prototype.namespace = function() {
var klasses = arguments[0] || {};
return _namespace(this.valueOf(), klasses);
};
/**
* @see Namespace.include()
*/
String.prototype.include = function() {
var callback = arguments[0] || false;
return _namespace.include(this.valueOf(), callback);
        };
/**
* @see Namespace.use()
*/
String.prototype.use = function() {
var callback = arguments[0] || false;
return _namespace.use(this.valueOf(), callback);
        };
/**
* @see Namespace.from()
*/
String.prototype.from = function() {
return _namespace.from(this.valueOf());
        };
/**
* @see Namespace.provide()
* Idea and code submitted by Nathan Smith (http://github.com/smith)
*/
String.prototype.provide = function() {
return _namespace.provide(this.valueOf());
        };
/**
* @see Namespace.use()
*/
Array.prototype.use = function() {
var callback = arguments[0] || false;
return _namespace.use(this, callback);
        };
/**
* @see Namespace.provide()
*/
Array.prototype.provide = function() {
return _namespace.provide(this);
        };
};

return _namespace;
})();

/**
* Namespace segment separator
*
* @var String
*/
Namespace.separator = '.';

/**
* Base uri when using Namespace.include()
* Must end with a slash
*
* @var String
*/
Namespace.baseUri = './';

/**
* Whether to automatically call Namespace.include() when Namespace.import()
* does not find the targeted object.
*
* @var Boolean
*/
Namespace.autoInclude = true;